Machine for operating on commutators.



S. D. HARTOG.

MACHINE PoR OPERATING 0N coMMUTAToRs.

APPLIUATION Hmm MAY 2o, 1912.

Patented Aug. 19, 1913.

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Specication ot Letters Intent.

Patented Aug. 19,1913.

Application am my 2o, 1.912. serial no. 698,662.

To all 'whom t may concern.'

Be it known that I, STEPHEN D. a citizen of the United' States, and residing at St. Louis, in the State of Missouri, have invented certain new and useful Improvements in Machines for Operating on Commutators, of which the following is a speciication.

This invention relates to a device for'cu-'tting down the mica' or insulation between the bars of commutatore of electrical machinery.-

Certain types of electrical machines such as dynamos and motors are provided with commutators composed of copper bars or segments separated lby sheets of mica or other insulation, and the current is conducted to and from the machine by brushes bearing upon the commutator. It is `found in practice that the copper bars wear down .faster than the mica sheets, so that in course of time the mica will project above the copper bars, causing sparking at the brushes. It is not desirable to turn down the' entire commutator in a lathe every time this condition of aiairs arises, in view of the fact that the commutator may be otherwise entirely true, and it is not desirable to take a cut from the copper bars unless necessary, as this not only results in wearing down of the commutator, but it is diiricult to regain the smooth finish of the commutator. surface. It has therefore been the practice to'dress down the projecting mica by hand with a file. This however 1s'a very laborious task,

las an ordinary commutator has a large number of segments, and moreover the use of a hand file rounds oi and mutilates the copper bars, thus resulting' in an uneven commutator surface. e

One of the objects of this invention therefore is to construct a Vdevice by means of which the height of the mica or insulation can be reduced rapidly, accurately, and without requiring a large expenditureof manual labor.

Another object is to construct a device which will be in the form of an attachmentl Fig. 2' is a section on thev line 2--2 Fig, 1,-

HAnme,

and t coperating raceways arranged to receive iba'lls .19 to form a .thrust bearing between and closing '22. The

Fig. 3 asection on' the line 3-3 Fig. 1,

Fig. 4is a plan view of the device with' the Idri-ving'head removed, Fig. 5 is a 'bottom jview 'of the driving. head, and 'is a fview illustrating the operation of the device.

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Referring to the accompanying drawings,

;10` designates a support or body provided ideway for a Slide orV -rcarrier 11. This sllde is slotted to receive a witli a transverse cutter blade 12 which is clamped therein by imeans of screws, and which is reduced in thickness to forma thin toothed cutting edge fas shown in Figs, 1 and 2. jcarrier. 11 extends through a 'slot in thevv 'support and is provided at its upper end :with a cam roll 14. The su A pin 13 on the formed thereon a boss 1.5 which is formed 4lecllowtic provide a bearing for a driving 'head 16. y This driving head is provided with a reduced bearing portion 17 entering the bearing in the boss and is provided at lits lower end with Van eccentric cam groeve The boss 15 18 engaging the cam roll 14.

e driving head 16 are provided with the support and the driving head, The boss and the bearing portion 17 are further projvided with coperating raceways. for a series -of balls 20 which forni a circumferential bearing between the support arid the driving head. It will be understood that the diameter of the bearing portion 17 is slightly less than the diameter of the bearin in the boss Vl5. The device is assembled y inserting the driving head into the support, placing the balls 19 in position, inserting the balls 20 through an aperture 21 in the boss 15, the aperture by means of a plug riving headl is provided with a tapered shank 23 arranged to -b'e inserted into a tool holder such as a drill press spindle, and the support 10 is provided with tapped holes 24 arranged to receive a threaded rod or the like. If the shank 23 is inserted into a tool holder such as a drill press s indle, and the drill press spindle revolve while the support isheld against movement, then the rotation of the driving head will canse rapid reciprocation of the cutter in its guideway.

It will be ncted'that the balls 19 and 20 provide an accurate and smooth roller bearing between the driving head and the supp'ort, and that the series of balls 20 hoid the driving head and support together against endwise separation. The driving* head can be readily removed by removing' the plug 22 and removing the balls 2O through the side aperture 2l.

Referring now to Fig. 6 in which 30 des ignates an armature of an electrical machine provided with a commutator 3l and a drive shaft 32, 33 designates a stand or bracketwhich is arranged to support the armature upon the table of a drill press. It will be understood of course that a pair of end bearings 34 is provided for the armature shaft, and that the caps of these bearings are arranged to grip and frictionally hold the armature shaft. Since however such supporting brackets are of common construction, a detail description will' be unnecessary. The object is to provide a stand for supporting the armatule and the commutator thereon in proper coperative relation with respect to the tool' holder or drill press spindle. lIt is possible to support the armature in its own field frame, which may rest on the drill press table or on the floor. The shank 23 is inserted into the drill press spindle 35 and will be frictionally held therein. A rod 36 threaded at its lower end is fastened in one of the tapped holes 24 of the support 10, and this rod is preferably bent laterally as shown at 37 to engage one side of the spindle bearing arm 38 of the drill press and hold the support against rotation. After the device is in position, the commutatoris alined with the device so as' to posit-ion the mica in alinement with the edge of the cutter 12 as shown in Fig. 6. rlhe drill press clutch 'is now thrown in which causes the cutter to reciprocate rapidly, and the drill press spindle is then depressed so as to cause the cutter to engage the mica as shown in Figs. 2 and 6. This engagement ofthe cutter will. cause the mica to be cut down, the cutter entering between the commutator segments. Each mica` strip can in turn be brought beneath the cutter 12 by rotating the armature, the armature being held in posit-ion by the frictional engagement of its shaft with the stand bearings. In Fig. 2 is illustrated a part of a commutator showing three sheets of mica, the one to the right of the cutter projecting above the commutator, and the one to the left 'of the cutter having been cut down. The mica is cut down slightly below the surface of the commutator so that the commutator can be used for some time before the copper will wear down below the mica. The drill press spin` dle can of course be provided with the usual stop for limiting its downward movement so as to limit the depth of the cut. The thickness of the cutter edge is substantially Iequal to the thickness of the mica, and in practice cutters of different thicknesses are provided, which cutters may be interchangei,crdeee F1fably inserted in the cutter carrier. As the length of the stroke of the cutter can be made suiiicient to cover the entire length of the brush surface ofthe commutator, each mica strip can be cut down by a single op` eration. It will thus be seen that the operation is exceedingly rapid and eiiicient.

It is obvious that various changes may be made in the details of construction, within the scope of the appended claims, without departing from this invention, and it is therefore t0 be understood that this invenstruction shown and described.

Having thus described the invention what is claimedis:

l. In a device of the class described, the combination with means for supporting a commutator, of a cutter blade having a cutting edge constructed and arranged to enter betweenthe bars of the commutator and reduce the height of the insulation therebetween, means for supporting said cutter to position its cutting edge parallel with the commutator bars and the insulation therebetween, and means for moving said cutter toward and from said commutator.

2. In a device of the class described, the combination with means for supporting a commutator, of a cut-ter blade having a cutting edge constructed to ent-er between the bars of the commutator and reduce the height of the insulation therebetween, means for supporting said cutter to position its cutting edge along the commutator bars, means for reciprocating said cutter in a path along the commutator bars, and means for moving said cutter toward said commutator.

3. An attachment of the class described comprising a portable support, a cutter on said support, and a rotary member on said support having an operative connection with said cutter and forming a carrier for said attachment.

4. An attachment of the class described comprising a portable support, a` cutter on said support, and a rotary member on said support having an operative connection with said cutter and constructed to be attached to a driving member, said rotary member forming a carrier for saidv attachment.

5. An attachment of the class described comprising a portable support having a transverse guideway thereon, a cutter mounted to reciprocate in said guideway, a driving head rotatively mounted in said support and having a drivin connection with said cutter, and an attachlng shank on said driving head adapted to be attached to a driving member.

6. An attachment of the class described comprising a ortable support having a transverse gui eway, a cutter mounted on said support to reciprocate in said guidetion is not to be limited to the specific conllt way, a driving head rotatively mounted in said support, an attaching shank on said driving head adapted to be attached to a driving member, and means for removably retaining said driving head in said support.

7. An attachment of the class described comprising a portable support having means for attaching it to a driving device, a cutter on said support, a driving head rotatively mounted in said support, and rollers between said driving head and said support forming means for removably retaining said driving head in said support.

8. An attachment of the class described comprising a portable support having a guideway thereon, a projecting cutter mounted in said guideway and having a cutting edge extending lengthwise thereof, a rotary driving head on said support. adapted to make a driving connection with a driving device when the attaclnnent is attached thereto, and means connecting said driving head with said cutter to cause said driving head to reciprocate said cutter.

i 9. An attachment of the class described comprising a portable support having va guideway thereon, a reciprocating cutter mounted in said guideway and projecting beyond said -support in adirection trans-A versely to the line of movement of said cutter, a rotary driving head on said support adapted to make a driving connection with a driving device'when t-he attachment is attached thereto, and an operative connection between said driving head and said cutter constructed to cause said driving head to reciprocate said cutter. i

l0. An attachment of the class described comprising a port-able support having a guideway thereon, a reciprocating cutter mounted in said guideway and projecting beyond said support in a direction transversely to the line 'of movement ot said cutter, a rotary driving head on said support adapted to make a driving connection with a driving device and form an attaching carrier for said attachment, and an operative connection 'between said driving head and said cutter constructed to cause said driving head to reciprocate said cutter.

l1. An attachment 'of thc class described comprising a port-able support rhaving a guideway thereon, a reciprocating cutter mounted in said guideway and projecting beyond said support in a direction transversely to the line of movement of said cutter, .a rot-ary driving head having an attach.

ing shank adapted to be connected to a driving device to form an operative driving connection therewith and carry 4and support the attachment onsaid driving device, and an operative connection between said driving head and said cutter constructed to cause said driving head to reciprocatesaid cutter. 12. An attachment of the class described comprising a portable support having a guideway thereon, a reciprocating cutter mounted in said guideway and projecting beyond said support in a direction transversely to the line of movement of said cutter, a rotary driving head extending into said support and having an operative connection with said cutter to reciprocate the same, means connecting said driving liead and support constructed to permit said driving head to carry said support, and an attaching shank on said driving head adapted to be connected to a driving device to form an operative driving connection therewith and carry and support the attachment on said driving device'.

13. An attachment of the class described comprising aportable support having aguideway thereon, a reciprocating cut-ter mounted in said guideway and projecting beyond said support in a direction transversely to the line of movement of said cutter, and adapted to enter between `the bars ofl a commutator and cut the insulation therebetween, and means on said support for reciprocating said cutter adapted to make a driving connection with a driving device when the attachment is attached thereto.

l 14. An `attachment of the class described comprising a portable support havingA a guideway thereon, a projecting cutter mounted in saidA guideway and having a cutting edge extending lengthwise thereof and adapted to be positioned along and enter between the bars of a commutator and cut the insulation therebetween, a rot-ary driving head on said support adapted to make a driving connection with a driving device when the attachment is attached thereto, and means connecting said ldriving head with said cutter to cause said driving head to reciprocate said cutter.

In testimony whereof I aiix my signature in presence of two witnesses.

STEPHEN D. HARTOG. lVitnesses J. H. BRUNINGA, FRANKLIN MILLER. 

